This invention relates to a method and apparatus for producing drinking water from impure water and more particularly, it relates to a portable apparatus and method for producing drinking water from impure water using microfiltration and reverse osmosis.
In the past, many devices have been proposed for producing drinking water from contaminated water. For example, U.S. Pat. No. 5,059,317 discloses an installation for filtering drinking water out of contaminated water, which can be used in many different situations. It consists of a hydrocyclone, a micro filter unit, a unit for reverse osmosis, a mixed bed ion exchange, a re-salting unit, a unit for oxonization, an activated carbon filter and a unit for chlorinization.
Also, U.S. Pat. No. 5,244,579 discloses a self-contained, transportable reverse osmosis water purification unit which has a limited throughput of no more than about 20 gpm of permeate in a single pass operation with reverse osmosis ("RO") modules which can be cleaned in place. When raw water is particularly fouled, the unit is operated in a double pass operation in which the permeate from the first pass is used as feed for a second RO module. A high pressure pump is required to feed water freed from suspended solids to the RO modules. The pump also delivers concentrate to a bladder tank where the concentrate is stored under pressure (about 100 psig) to flush a coarse filter automatically when it is plugged. Fine filters for solids removal can be replaced when the unit is not producing permeate.
U.S. Pat. No. 3,992,301 discloses an automatic flushing and cleaning system for membrane separation machines such as reverse osmosis machines having plural modules or membranes. Cleaning may be by way of reducing the pressure to allow the membrane to relax, by the injection of air or inert gas to provide turbulence, and/or by injection of flushing liquid which may include chemical cleaning additives. Pumps, automatic valving, and pressure controls are provided, along with a complete timer operated electrical sequencing system whereby desired purging, flushing and cleaning cycles are automatically undertaken at periodic intervals or in response to one or more preferred conditions.
U.S. Pat. No. 4,842,724 discloses self-standing apparatus for filtering supply water to provide purified water which includes a base subassembly and two container subassemblies. One container subassembly provides supply water to filtering apparatus located in the base subassembly. The second container holds purified water which passes through a semipermeable membrane filter in the base subassembly. Concentrate from the membrane filter flows back to the supply water container for ultimate recirculation. The base subassembly and the container subassemblies have automatically closing valves which render each container water-tight when separated from the base subassembly, and which open to provide communication between the containers and filtering apparatus within the base subassembly.
U.S. Pat. No. 4,670,144 discloses a portable water purification system including a generally rectangular boxlike chest containing a particulate matter prefilter, a reverse osmosis filter and an activated carbon postfilter unit disposed in a lower base part of the chest. The prefilter, reverse osmosis filter and post-filter units are connected in series by flexible conduits.
U.S. Pat. No. 5,004,535 discloses a reverse osmosis water purification system including a support structure dimensioned and arranged to facilitate manual transportation, purification components mounted on the support structure for producing product water and waste water from feedwater by reverse osmosis, the pump components mounted on the support structure for pumping feedwater from a separate source to the purification means.
U.S. Pat. No. 5,589,066 discloses a portable water purification system which has a prefilter, a pumping unit, a reverse osmosis unit, a microbial control unit and a post filter for removing nuclear, biological, chemical and other contaminants from a water source. The hand operated pumping unit has a feed water cylinder and a concentrate cylinder to control ratios between intake and concentrate volumes. The system further prolongs the life of components by reducing the level of contaminants in contact with parts of the system.
Other patents disclosing water purification systems include U.S. Pat. Nos. 5,223,132; 5,282,972; 5,403,479; 5,501,798; 5,520,816; 5,560,393; 5,585,531; 5,632,892; 5,647,973; 5,676,824; and 5,685,980.
In spite of these disclosures, there is still a great need for a portable water purification unit which can economically and efficiently produce potable water from impure or contaminated water.